Quantitative Interpretation of Seismic Deformation in Iran

Monday, 15 December 2014
Zoya Zarifi1, Mohammad Raeesi2, Faramarz Nilfouroushan1 and Kristy French Tiampo3, (1)Uppsala University, Uppsala, Sweden, (2)University of Bergen, Earth Sciences, Bergen, Norway, (3)University of Western Ontario, London, ON, Canada
Iranian plateau, as part of Eurasian plate wedged between Arabian and Indian plates, is a zone of active tectonic where experiences destructive earthquakes frequently. Quantitative interpretation of seismicity and their comparison with measured geodetic strain rate can provide invaluable information to assess the seismic hazard potential in Iran. We used seismicity recoded by national (2006-Present) and international (1909- Present) networks as well as geodetic data (1999-2011) to compute seismic strain rate, variation in source strength (Potency), rock mass resistance to the flow of coseismic inelastic deformation (Seismic viscosity) and their correlation with measured geodetic strain rate.

Our results suggest lower seismic strain rate along North Tabriz fault, central and NE Alborz and distinct areas in NE of Iran. These areas are associated with higher seismic viscosity suggesting quiescence time, however surrounded by lower seismic viscosity, which implies the easier flow of seismic inelastic deformation or greater stress transfer due to seismicity. Major historical earthquakes (more than 10 earthquakes with M>7, occurred before 1909) associated with suggested area in the northern Iran and the observed seismo-tectonic behavior may imply the potential seismic hazard in these regions.